Safety pump plunger



Jan; 9, 1940. H. E. BRANDT SAFETY PUMP PLUNGER Filed Feb. 25,, 1958 Ma JZ m M. n llll :1 a M, u WM 0w III .fi I; M -1 a, a a v I v 4 M L lm eflzar HEN/WE 21mm afl Patented Jan. 9, 1940 TES' 2,186,623 SAFETY PUMP PLUNGER. Henry s, Brandt, North St. Paul, Minn Application February 25, 1938, Serial. No. 192,522

2 Claims.

This invention relates to a, plunger structure for a pump and while the invention may be applicable to various pump plungers, it is illustrated as used in an air pump one specific use of which is for a spraying or liquid discharge device in which the liquid is placed under pressure. 1

In such liquid discharge devices as stated, the liquid in the container is placed under pressure and it may happen that excessive air pressure will be put on the liquid through the pumping means, which excessive pressure may cause damage to the device or cause an Objectionable discharge of the liquid. It is desirable therefore, to regulate the pressure which can be put on the liquid or, in other words, produced in the container. I

It is an object of this invention therefore, to

provide a simple and efficient structure of pump er having means through which air may pass to v bypass said plunger and means engaging said means to prevent said passage of air including a spring and preferably means for adjusting the tension of said spring toregulate the pressure at which air may bypass the plunger.

These and other objects and advantages of the invention will be fully set forth in the following description made in connection with the accompanying drawing in which like reference characters refer to similar parts throughout the several views and in which:

Fig. l is for the most part a central vertical section through a portion of a pump cylinder and plunger construction embodying the invention; and

Fig. 2 is a View in horizontal section taken on line 22 as indicated by the arrows, a portion being broken away.

Referring to the drawing a pump cylinder ii! is shown which preferably will be made of some suitable and comparatively thin metal. A plunger rod l I is disposed axially of said cylinder, the same beingthreaded at its lowerend as shown at No. A nut i2 is threaded onto the lower end of rod ii, the same being shown as engaging a spring split washer l3. Washer It in. turn engages the lower side of a plate it apertured for plunger i l to pass therethrough and being formed at its outer portion into an annular trough having an upper open side. The inner portion of plate M has a plurality of circumferentially engaging the upper end of .cylinder I0.

spaced holes I401. therethrough. A wick E5 of felt or other similar material, is disposed in the trough of plate It and is thus of annular form. Wick l5 will contain a suitable lubricant and said wick is shown as engaging atits upper side 5 with a plunger it which will be made of some flexible material such as leather or some rubber and fabric composition. Plunger It is shown as generally of cup-shape, the same having a cylinrical wall liia engaging the inner side of cylinder iii. Said plunger is shown as somewhat curved and the same thus has an open or concave side and an upper closed or convex side. A plate i'i' overlies plate It and is apertured to have plunger H pass therethrough and has an outer annular ofiset portion overlying the upper or convex portion of plunger IS. The inner or depressed portion of plate ll isprovided with a plurality of apertures Ila. A washer E8 of leather, fabric or fiber composition overlies the inner or depressed portion of plate H and covers the apertures ila. A sleeve 19 surrounds plunger H and passes shown at lib to have expanded portions preventing further upward movement of nut 22. A coiled compression spring 23 rests loosely on nut 22 surrounding rod M and acts as a buffer spring for In operation, when air is-to be pumped, rod II will be reciprocated. When the same is lifted air will be drawn into the cylinder Hi below the plunger, said air passing around the plunger. Plunger it? may move somewhat longitudinally of rod Ii and in the intake stroke engages wick i :5. It is then slightly separated from plate ll and air can pass around the edge of plate il', through the central opening in plunger 15 and through the openings I la. When the rod is moved downwardly the air in cylinder it will be forced downwardly, plunger i5 will tightly-engage the undersuriace of plate ,ll so that no-air can pass theplunger and the holes Ha will be kept closed by members-I8 and it due tothe pressure of spring i9. Should the pump be operated until the pressure below the g plunger exceeds the strength or tension of spring 19 air will pass through the openings Ma and through openings Ho and lift members l8 and 20 against the tension of spring l9. Air can pass around members I8 and 20 after passing through holes l'la and bypass the plunger. It will thus be impossible to create a pressure below the plunger or in the container into which air is being pumped which is greater than the tension of spring H3. The tension of spring I9 may be varied by adjustment of nut 22 so that the pressure to be obtained may be varied.

From the above description it isseen that I have provided a very simple, eificient and compact structure of plunger which will act to limit the amount of pressure which may be pumped by the pump comprising the same. The necessary parts for obtaining this result are very few and of very simple, rugged and inexpensive construction.

The device has been amply demonstrated in actual practice, found to be very successful and the same is being commercially made.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts, without departing from the scope of applicants invention,

, which generally stated, consists in a device capable of carrying out the objects above set forth, in the parts and combinations of parts disclosed and defiined in the appended claims.

What is claimed is:

l. A pump plunger structure having in combination, a plunger rod, a cup shaped plunger of flexible material having a central opening surrounding said rod, a rigid backing member at the concave side of said plunger having an imperforate central portion surrounding said rod and openings outwardly thereof beyond said central portion, a plate having an outer annular portion disposed above said plunger and a central portion engaging the imper'forate portion of said backing member and having a plurality of openings therethrough, a sleeve surrounding said rod, means surrounding said sleeve overlying said plate and closing said openings and resilient means urging said last mentioned means against said plate.

2. A pump plunger structure having in combination, a plunger rod, a cup shaped plunger of flexible material having a central opening surrounding said rod, a plate overlying the convex side of said plunger outwardly of said opening and having a central portion with a plurality of apertures therethrough, a second plate disposed at the concave side of said plunger having a central portion engaging the central portion of said first mentioned plate, a sleeve surrounding said rod engaging said first mentioned plate at its lower end, means surrounding said sleeve overlying said first mentioned plate and adapted to close the apertures therethrough, a spring surrounding said sleeve having its lower end engaging said means, adjustable means on said rod engaging the upper end of said spring and adapted to be limited in its movement by the upper end of said sleeve.

HENRY E. BRANDT. 

